You may want to try something simple, like checking the throttle and cruise control linkage and make sure they allow the throttle valve to close fully. Also check that the throtle valve closes fully without sticking.
MAster cylinder and exhaust leaks do not affect idle speeed. However, a leaky power brake booster will. Also the opti is capable of doung silly things also. I had one that would cause the engine to rev up for no reason while stopped at a light.

 

try checking the tps did you take it off if so did you adjust it when you put it back on

 

If you want to scan your car, try using an ALDL to USB cable. My friend uses it on his '95 because the OBD connector in relation to the system is a bit goofy.
OBD Diagnostics, Inc. - ALDL (GM OBD1) Cable with 16 pin Connector
There's diagnostic software included that can be installed on a laptop.

As for fixing the car, go with the Jeremy Clarkson method of auto repair, i.e. hit it with a hammer. If that doesn't work, buy a bigger hammer.

 

Well the tps is like spring loaded it seems. It goes back to it's original spot with no twisting force applied. The throttle body closes all the way. What do you mean the oti cable?

 

And catmaigne I would be all for that....but no computer. Just an iphone